U.S. patent number 6,120,905 [Application Number 09/094,864] was granted by the patent office on 2000-09-19 for hybrid nonisocyanate polyurethane network polymers and composites formed therefrom.
This patent grant is currently assigned to Eurotech, Ltd.. Invention is credited to Oleg L. Figovsky.
United States Patent |
6,120,905 |
Figovsky |
September 19, 2000 |
Hybrid nonisocyanate polyurethane network polymers and composites
formed therefrom
Abstract
This invention relates to a hybrid nonisocyanate polyurethane
network polymer formed by cross-linking at least one cyclocarbonate
oligomer and at least one amine oligomer. The cyclocarbonate
oligomer contains a plurality of terminal cyclocarbonate groups. At
least one cyclocarbonate oligomer further comprises from about 4%
to about 12% by weight of terminal epoxy groups. Because at least
one cyclocarbonate oligomer contains both cyclocarbonate and epoxy
reactive groups, the network formed therefrom is referred to as a
hybrid nonisocyanate polyurethane network. The cyclocarbonate
oligomer or oligomers have an average functionality towards primary
amines of from about 2.0 to about 5.44. The amine oligomer
comprises at least one primary amine-terminated oligomer terminated
with primary amine groups and has an average functionality towards
cyclocarbonate groups of from about 3.0 to about 3.8. The amine
oligomer is present in an amount from about 0.93 to about 0.99 of
the amount of the amine oligomer that would be required to achieve
a stoichiometric ratio between the primary amine groups of the
amine oligomer and the cyclocarbonate groups of the cyclocarbonate
oligomer. The hybrid nonisocyanate polyurethane network polymer
formed has a gel fraction of not less than about 0.96 by weight.
This invention also relates to methods of making hybrid
nonisocyanate polyurethane networks and their use as a composite
matrix material.
Inventors: |
Figovsky; Oleg L. (Haifa,
IL) |
Assignee: |
Eurotech, Ltd. (Washington,
DC)
|
Family
ID: |
22247637 |
Appl.
No.: |
09/094,864 |
Filed: |
June 15, 1998 |
Current U.S.
Class: |
428/425.6;
525/423; 528/106; 528/121; 528/407 |
Current CPC
Class: |
C08G
71/04 (20130101); Y10T 428/31601 (20150401) |
Current International
Class: |
C08G
71/04 (20060101); C08G 71/00 (20060101); B32B
027/40 () |
Field of
Search: |
;525/423
;528/106,121,407 ;428/425.6 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
246901 |
|
Jun 1987 |
|
DE |
|
3723782C2 |
|
Jan 1989 |
|
DE |
|
1353792 A1 |
|
Nov 1987 |
|
SU |
|
1754748 A1 |
|
Aug 1992 |
|
SU |
|
Other References
WJ. Blank, "Non-Isocyanate Routes to Polyurethane", Proceedings of
the 17.sup.th Water-Borne and Higher Solids CoatingS Symposium, New
Orleans, LA, Feb. 21-23, 1990, pp. 279-291. .
Oleg L. Figovsky, et al. "Non-Isocyanate Polyurethane",
Polyurethanes World Congress '97, Amsterdam, Sep. 29-Oct. 1, Poster
No. 70, pp. 1-7. .
O.L. Figovsky, "Improving the Protective Properties of Nonmetallic
Corrosion--Resistant Materials and Coatings", J. Mendeneev Chem.
Soc., 33(3) : 31-36 (1988). .
"Kirk-Othmer Encyclopedia of Chemical Technology", 4.sup.th Ed.,
vol. 1, pp. 913-925 (1991); vol. 77 pp. 1-60 (1993); pp. 730-755
(1994)..
|
Primary Examiner: Dawson; Robert
Assistant Examiner: Aylward; D.
Attorney, Agent or Firm: Pennie & Edmonds LLP
Claims
What is claimed is:
1. A network nonisocyanate polyurethane polymer formed by
cross-linking a cyclocarbonate oligomer and an amine oligomer,
wherein the cyclocarbonate oligomer has an average functionality
towards primary amines from about 2.0 to about 5.44,
wherein the cyclocarbonate oligomer comprises at least one
cyclocarbonate-terminated oligomer terminated with a plurality of
cyclocarbonate groups,
wherein at least one cyclocarbonate-terminated oligomer further
comprises from about 4% to about 12% by weight of terminal epoxy
groups based on the weight of terminal cyclocarbonate groups
present,
wherein the amine oligomer has an average functionality towards
cyclocarbonate groups of from about 3.0 to about 3.8,
wherein the amine oligomer consists essentially of at least one
primary amine-terminated oligomer, wherein each primary
amine-terminated oligomer is terminated with a plurality of primary
amine groups, wherein each primary amine group is linked to the at
least one primary amine-terminated oligomer by a linking group
comprising, independently, from at least one to about twelve carbon
atoms, a first end and a second end, wherein the first end of each
linking group is bonded to the nitrogen atom of the primary amine
group and the second end of each linking group is bonded to the
amine oligomer, and wherein each linking group carbon atom adjacent
to the nitrogen atom of each primary amine group is independently
selected from the group consisting of a methylene carbon atom and a
methine carbon atom, provided that,
(1) when the second end of the linking group is bonded to an
aliphatic ring, the linking group comprises at least one methylene
carbon atom wherein the first end of the linking group comprises
the methylene carbon atom,
(2) when the second end of the linking group is bonded to an
aromatic ring, the linking group comprises at least two adjacent
methylene carbon atoms wherein the first end of the linking group
comprises the two adjacent methylene carbon atoms, and
(3) when the second end of the linking group is bonded to an amine
oligomer comprising siloxane groups, the linking group comprises at
least three adjacent methylene carbon atoms wherein the first end
of the linking group comprises the three adjacent methylene carbon
atoms,
wherein the amine oligomer is present in an amount from about 0.93
to about 0.99 of the amount of the amine oligomer that would be
required to achieve a stoichiometric ratio of the primary amine
groups of the amine oligomer to the cyclocarbonate groups of the
cyclocarbonate oligomer, and
wherein the network polymer formed has a gel fraction of not less
than about 0.96 by weight.
2. The network nonisocyanate polyurethane polymer of claim 1,
wherein the average functionality of the cyclocarbonate oligomer
towards primary amines ranges from about 2.6 to about 5.3.
3. The network nonisocyanate polyurethane polymer of claim 1,
wherein the gel fraction is not less than about 0.975.
4. The network nonisocyanate polyurethane polymer of claim 1,
wherein the gel fraction is not less than about 0.980.
5. The network nonisocyanate polyurethane polymer of claim 1,
wherein the cyclocarbonate-terminated oligomer has a number average
molecular weight of from about 350 g/mol to about 3,200 g/mol.
6. The network nonisocyanate polyurethane polymer of claim 5,
wherein the cyclocarbonate-terminated oligomer has a number average
molecular weight of from about 700 g/mol to about 1400 g/mol.
7. The network nonisocyanate polyurethane polymer of claim 1,
wherein the cyclocarbonate-terminated oligomer has a viscosity at
25.degree. C. of from about 150 mPa.s to about 8,800 mPa.s.
8. The network nonisocyanate polyurethane polymer of claim 7,
wherein the cyclocarbonate-terminated oligomer has a viscosity at
25.degree. C. of from about 350 mPa.s to about 1,500 mPa.s.
9. The network nonisocyanate polyurethane polymer of claim 1,
wherein the cyclocarbonate-terminated oligomer comprises at least
one material selected from the group consisting of di-carbonate,
tri-carbonate, tetra-carbonate and penta-carbonate ester, ether or
amine derivatives of aromatic or aliphatic compounds comprising
from 2 to 5 terminal functional groups selected from the group
consisting of hydroxy groups, amine groups, and mixtures
thereof.
10. The network nonisocyanate polyurethane polymer of claim 1,
wherein the cyclocarbonate-terminated oligomer comprises at least
one material selected from the group consisting of ##STR13##
wherein m.sub.1, m.sub.2 and m.sub.3 are independently selected
over the range from 3 to 12 inclusive and wherein
0.ltoreq.n.ltoreq.6, ##STR14## wherein 0.ltoreq.n.ltoreq.4,
##STR15##
11. The network nonisocyanate polyurethane polymer of claim 1,
wherein the at least one terminal epoxy group comprising
cyclocarbonate-terminated oligomer consists essentially of a
remainder and an epoxy group, wherein the epoxy group is bonded to
the remainder by at least one primary carbon atom adjacent to the
epoxy group.
12. The network nonisocyanate polyurethane polymer of claim 1,
wherein the primary amine-terminated oligomer has a number average
molecular weight of from about 60 g/mol to about 3,900 g/mol.
13. The network nonisocyanate polyurethane polymer of claim 12,
wherein the primary amine-terminated oligomer has a number average
molecular weight of from about 180 g/mol to about 880 g/mol.
14. The network nonisocyanate polyurethane polymer of claim 1,
wherein the primary amine-terminated oligomer has a viscosity at
25.degree. C. of from about 10 mPa.s to about 2,800 mPa.s.
15. A network nonisocyanate polyurethane polymer formed by
cross-linking a cyclocarbonate oligomer and an amine oligomer,
wherein the cyclocarbonate oligomer has an average functionality
towards primary amines from about 2.0 to about 5.44,
wherein the cyclocarbonate oligomer comprises at least one
cyclocarbonate-terminated oligomer terminated with a plurality of
cyclocarbonate groups,
wherein at least one cyclocarbonate-terminated oligomer further
comprises from about 4% to about 12% by weight of terminal epoxy
groups based on the weight of terminal cyclocarbonate groups
present,
wherein the amine oligomer has an average functionality towards
cyclocarbonate groups of from about 3.0 to about 3.8,
wherein the amine oligomer comprises at least one primary
amine-terminated oligomer terminated with a plurality of primary
amine groups,
wherein the primary amine-terminated oligomer has a viscosity at
25.degree. C. of from about 50 mPa.s to about 750 mPa.s,
wherein the amine oligomer is present in an amount from about 0.93
to about 0.99 of the amount of the amine oligomer that would be
required to achieve a stoichiometric ratio of the primary amine
groups of the amine oligomer to the cyclocarbonate groups of the
cyclocarbonate oligomer, and
wherein the network polymer formed has a gel fraction of not less
than about 0.96 by weight.
16. A network nonisocyanate polyurethane polymer formed by
cross-linking a cyclocarbonate oligomer and an amine oligomer,
wherein the cyclocarbonate oligomer has an average functionality
towards primary amines from about 2.0 to about 5.44,
wherein the cyclocarbonate oligomer comprises at least one
cyclocarbonate-terminated oligomer terminated with a plurality of
cyclocarbonate groups,
wherein at least one cyclocarbonate-terminated oligomer further
comprises from about 4% to about 12% by weight of terminal epoxy
groups based on the weight of terminal cyclocarbonate groups
present,
wherein the amine oligomer has an average functionality towards
cyclocarbonate groups of from about 3.0 to about 3.8,
wherein the amine oligomer comprises at least one primary
amine-terminated oligomer terminated with a plurality of primary
amine groups,
wherein the primary amine-terminated oligomer comprises at least
one material selected from the group consisting of aminosilane
oligomers with a functionality toward terminal-cyclocarbonate
groups of from about 3 to about 7, oligovinyl ethers of
monoethanolamine with functionality toward terminal-cyclocarbonate
groups of from about 3 to about 8, monomeric triamines, monomeric
tetraamines, polypropylenetriamine, polypropylenepentamine, and
mixtures thereof,
wherein the amine oligomer is present in an amount from about 0.93
to about 0.99 of the amount of the amine oligomer that would be
required to achieve a stoichiometric ratio of the primary amine
groups of the amine oligomer to the cyclocarbonate groups of the
cyclocarbonate oligomer, and
wherein the network polymer formed has a gel fraction of not less
than about 0.96 by weight.
17. A network nonisocyanate polyurethane polymer formed by
cross-linking a cyclocarbonate oligomer and an amine oligomer,
wherein the cyclocarbonate oligomer has an average functionality
towards primary amines from about 2.0 to about 5.44,
wherein the cyclocarbonate oligomer comprises at least one
cyclocarbonate-terminated oligomer terminated with a plurality of
cyclocarbonate groups,
wherein at least one cyclocarbonate-terminated oligomer further
comprises from about 4% to about 12% by weight of terminal epoxy
groups based on the weight of terminal cyclocarbonate groups
present,
wherein the amine oligomer has an average functionality towards
cyclocarbonate groups of from about 3.0 to about 3.8,
wherein the amine oligomer comprises at least one primary
amine-terminated oligomer terminated with a plurality of primary
amine groups,
wherein the primary amine-terminated oligomer comprises at least
one material selected from the group consisting of
polyoxypropylenetriamine, tris-(3-aminopropyl)-cyanurate,
polypropylenetriamine, polypropylenepentamine, ##STR16## wherein
2.ltoreq.m.ltoreq.12, ##STR17## wherein m.sub.1, m.sub.2 and
m.sub.3 are independently selected over the range from 3 to 12
inclusive and wherein 1.ltoreq.n.ltoreq.3,
wherein the amine oligomer is present in an amount from about 0.93
to about 0.99 of the amount of the amine oligomer that would be
required to achieve a stoichiometric ratio of the primary amine
groups of the amine oligomer to the cyclocarbonate groups of the
cyclocarbonate oligomer, and
wherein the network polymer formed has a gel fraction of not less
than about 0.96 by weight.
18. The network nonisocyanate polyurethane polymer of claim 1,
wherein each linking group carbon atom adjacent to the nitrogen
atom of each primary amine group is a methylene carbon atom.
19. The network nonisocyanate polyurethane polymer of claim 1,
wherein each linking group adjacent to the nitrogen atom of each
primary amine group comprises at least two adjacent methylene
carbon atoms wherein the first end of the linking group comprises
the adjacent methylene carbon atoms.
20. A method of producing a network nonisocyanate polyurethane
polymer which comprises:
(a) selecting as a first oligomer at least one oligomer terminated
with a plurality of cyclocarbonate groups, said
cyclocarbonate-terminated oligomer further comprising from about 4%
to about 12% by weight epoxy groups based on the weight of terminal
cyclocarbonate groups present, wherein said first oligomer has an
average functionality towards primary amines of from about 2.0 to
about 5.44;
(b) selecting as a second oligomer at least one amine oligomer
terminated with a plurality of primary amine groups, wherein said
second oligomer has an average functionality towards cyclocarbonate
groups of from about 3.0 to about 3.8 and wherein the amine
oligomer consists essentially of at least one primary
amine-terminated oligomer, wherein each primary amine-terminated
oligomer is terminated with a plurality of primary amine groups,
wherein each primary amine group is linked to the at least one
primary amine-terminated oligomer by a linking group comprising,
independently, from at least one to about twelve carbon atoms, a
first end and a second end, wherein the first end of each linking
group is bonded to the nitrogen atom of the primary amine group and
the second end of each linking group is bonded to the amine
oligomer, and wherein each linking group carbon atom adjacent to
the nitrogen atom of each primary amine group is independently
selected from the group consisting of a methylene carbon atom and a
methine carbon atom, provided that,
(1) when the second end of the linking group is bonded to an
aliphatic ring, the linking group comprises at least one methylene
carbon atom wherein the first end of the linking group comprises
the methylene carbon atom,
(2) when the second end of the linking group is bonded to an
aromatic ring, the linking group comprises at least two adjacent
methylene carbon atoms wherein the first end of the linking group
comprises the two adjacent methylene carbon atoms, and
(3) when the second end of the linking group is bonded to an amine
oligomer comprising siloxane groups, the linking group comprises at
least three adjacent methylene carbon atoms wherein the first end
of the linking group comprises the three adjacent methylene carbon
atoms;
(c) mixing the oligomers in an amount to form a mixture with a pot
life such that the amount of the second oligomer present is from
about 0.93 to about 0.99 of the amount of the second oligomer that
would be required to achieve a stoichiometric ratio of the primary
amine groups of the second oligomer to the cyclocarbonate groups of
the first oligomer; and
(d) curing the mixture at a temperature of from about 10.degree. C.
to about 140.degree. C. to form a network polymer with a gel
fraction of not less than about 0.96 by weight.
21. The method of claim 20, wherein the first oligomer is selected
to further comprise at least one cyclocarbonate-terminated oligomer
wherein the reactive terminal groups consist essentially of
cyclocarbonate groups.
22. The method of claim 20, wherein the average functionality of
the first oligomer towards primary amines ranges from about 2.6 to
about 5.3.
23. The method of claim 20, which further comprises forming a
network polymer with a gel fraction of not less than about
0.975.
24. The method of claim 20, which further comprises forming a
network polymer with a gel fraction of not less than about
0.980.
25. The method of claim 20, which further comprises mixing the
oligomers at a pressure of from about 0.001 atm to less than about
1 atm.
26. The method of claim 20, which further comprises curing the
mixture at a temperature of from about 15.degree. C. to about
30.degree. C.
27. The method of claim 20, which further comprises curing the
mixture at a pressure of from about 1 atm to about 10 atm .
28. The method of claim 27, which further comprises curing the
mixture at a pressure of from about 2 atm to about 10 atm.
29. The method of claim 27, which further comprises curing the
mixture at a pressure of from about 3 atm to about 5 atm.
30. The method of claim 20, wherein the pot life is at least about
15 minutes at 25.degree. C.
31. The method of claim 20, wherein the pot life is at least about
2 hours at 25.degree. C.
32. The method of claim 20, wherein each cyclocarbonate-terminated
oligomer has a number average molecular weight of from about 350
g/mol to about 3,200 g/mol.
33. The method of claim 21, wherein each cyclocarbonate-terminated
oligomer has a number average molecular weight of from about 350
g/mol to about 3,200 g/mol.
34. The method of claim 20, wherein each cyclocarbonate-terminated
oligomer has a viscosity at 25.degree. C. of from about 150 mPa.s
to about 8,800 mPa.s.
35. The method of claim 21, wherein each cyclocarbonate-terminated
oligomer has a viscosity at 25.degree. C. of from about 150 mPa.s
to about 8,800 mPa.s.
36. The method of claim 20, wherein each oligomer terminated with a
plurality of primary amine groups has a number average molecular
weight of from about 60 g/mol to about 3,900 g/mol.
37. The method of claim 20, wherein each oligomer terminated with a
plurality of primary amine groups has a viscosity at 25.degree. C.
of from about 10 mPa.s to about 2,800 mPa.s.
38. A composite material comprising a matrix and a reinforcement,
wherein the matrix comprises the network nonisocyanate polyurethane
polymer of claim 1.
39. The composite material of claim 38, wherein the matrix is
present in an amount of from about 12 wt. % to about 45 wt. %.
40. The composite material of claim 38, wherein the reinforcement
is selected from the group consisting of a fiber reinforcement, a
particulate reinforcement, and mixtures thereof.
41. The composite material of claim 40, wherein the fiber
reinforcement is selected from the group consisting of glass fiber,
carbon fiber, basalt fiber, and mixtures thereof.
42. The composite material of claim 40, wherein the particulate
reinforcement comprises an active filler, wherein the active filler
is at least one material selected from the group consisting of a
metal oxide and a metal aluminate salt.
43. The composite material of claim 42, wherein the metal aluminate
salt is selected from the group consisting of copper aluminate,
calcium aluminate, lead aluminate, magnesium aluminate, zinc
aluminate, iron aluminate, and mixtures thereof.
44. The composite material of claim 42, wherein the metal aluminate
salt is selected from the group consisting of copper aluminate,
calcium aluminate, and mixtures thereof.
45. The composite material of claim 42, wherein the metal aluminate
salt is copper aluminate.
46. The composite material of claim 42, wherein the active filler
is present in an amount of from about 3 parts to about 200 parts by
weight based on 100 parts of the network nonisocyanate polyurethane
polymer.
47. The composite material of claim 46, wherein the active filler
is present in an amount of from about 10 parts to about 100 parts
by weight based on 100 parts of the network nonisocyanate
polyurethane polymer.
48. The composite material of claim 47, wherein the active filler
is present in an amount of from about 20 parts to about 40 parts by
weight based on 100 parts of the network nonisocyanate polyurethane
polymer.
49. The composite material of claim 42, wherein the mean particle
size of the active filler is less than or equal to about 30
.mu.m.
50. The composite material of claim 42, wherein the mean particle
diameter of the active filler is from about 2.5 .mu.m to about 30
.mu.m.
51. The composite material of claim 50, wherein the mean particle
diameter of the active filler is from about 4.5 .mu.m to about 15
.mu.m.
Description
TECHNICAL FIELD
The present invention is related to network polymers, more
specifically, to methods of producing hybrid nonisocyanate
polyurethane networks, based on reactions between oligomers
comprising terminal cyclocarbonate groups and oligomers comprising
terminal primary amine groups, and the hybrid network nonisocyanate
polyurethanes produced thereby.
BACKGROUND OF THE INVENTION
Hybrid network nonisocyanate polyurethane materials are completely
different, in structure and in properties, from linear and network
polyurethanes produced from oligomers and/or starting materials
comprising isocyanate groups.
The conventional method of producing linear and network
polyurethane compounds is based on the reaction between oligomers
with terminal hydroxyl groups and oligomers with terminal
isocyanate groups. This method is disadvantageous because it uses
toxic isocyanates, which are produced from an even more dangerous
component, phosgene. Another principal limitation of the
conventional polyurethane method of production is the more highly
porous material which it yields. Because the conventional
urethane-forming reaction is sensitive to moisture, an undesirable
side-reaction with water leads to the formation of carbon dioxide
gas within the polyurethane during its production. These gas
bubbles give rise to the increased porosity of such polyurethane
products.
Moreover, conventional polyurethanes derived from isocyanates are
not suitable for use in many applications, e.g., as composite
matrix materials, mastics, etc., because they have an inherent
weakness arising from their molecular composition. Within their
polymer structure are hydrolytically unstable chemical bonds which
make these materials highly vulnerable to environmental
degradation. For example, the use of conventionally produced
polyurethane matrix materials is limited by their hydrolytic
instability and their poor chemical resistance to aqueous solutions
of acids and alkalies.
By modifying the structure of the polymer, a promising method of
raising mechanical performance and hydrolytic stability is
introduced in the form of a nonisocyanate polyurethane network, a
modified polyurethane with lower permeability and increased
chemical resistance properties to aqueous solutions of acids and
alkalies. Moreover, nonisocyanate polyurethane networks are made by
a synthesis process that uses far more environmentally benign
materials than isocyanates and phosgene.
The preparation and properties of linear nonisocyanate
polyurethanes is disclosed by W. J. Blank ["Non-Isocyanate Routes
to Polyurethanes", Proceedings of the 17th Water-Borne and Higher
Solids Coatings Symposium, New Orleans, La., Feb. 21-23, 1990, pp.
279-291]. The preparation of a dihydroxy terminated nonisocyanate
polyurethane diol, its self-condensation, and the condensation of
this diol with other diols, such as polytetramethylene glycol and
hydroxy terminated polyester, is disclosed. However, this
publication does not teach that nonisocyanate polyurethane networks
may be formed, that a reactant comprising terminal cyclocarbonate
groups may be used to form a nonisocyanate polyurethane network, or
that a reactant comprising terminal primary amine groups may be
used to form a nonisocyanate polyurethane network.
Additionally, U.S. Pat. No. 5,340,889 to Crawford et al. discloses
a method for producing linear nonisocyanate polyurethanes based on
the reaction between the oligomeric bifunctional cyclocarbonate
oligomers described therein and amines. However, polyurethanes
formed by this method, because they lack a cross-linked network
structure, cannot be used for construction and structural
materials. Moreover, for the same reason, these materials are not
very chemically resistant to aqueous solutions of acids and
alkalies.
The above-described deficiencies in conventional linear
polyurethanes, conventional network polyurethanes and linear
nonisocyanate polyurethanes can be remedied by the formation of a
network comprising nonisocyanate polyurethanes. For example, after
hardening by cross-linking or curing, network nonisocyanate
polyurethanes may be used as the matrix of composite materials
which serve as structural components. Moreover, these materials are
also useful as:
nonporous monolithic coatings, coverings and linings, which can be
used for the corrosion protection and wear protection of concrete,
metallic and wood surfaces;
hydrolysis-stable and gasoline-stable sealants, which can be used
for protection of electronic devices and their components, in
aircraft and rocket construction and, mainly, for civil engineering
applications;
glues with high adhesion strength and longevity, which can be used
for joining all types of materials, e.g., metals, ceramics, glass,
etc.;
reinforced and highly-filled polymers, which can be used for civil
and chemical engineering applications.
Other potential areas where nonisocyanate polyurethane networks are
useful include automotive applications, such as for bumpers,
dashboards, seating, trim components, truck beds and repair putty;
construction applications, such as concrete additives, flooring and
crack barriers; marine applications, such as decking; and consumer
products, such as appliances, footwear, furniture and toys.
Nonisocyanate polyurethane matrices which are intended for
applications such as those described above must be characterized by
a relatively high level of mechanical properties, such as high
tensile strength and high relative elongation, and also have low
porosity, high hydrolytic stability and high chemical resistance to
aqueous solutions of acids and alkalies. Also, the process of
making these compounds is desirable because it uses nontoxic
reactants.
U.S. Pat. No. 1,754,748 discloses an epoxy resin-based composite
material used for monolithic flooring. The compositions of this
reference also contain an oligomeric dicyclocarbonate modifier and,
as a hardener, an aminophenol which is monofunctional toward the
cyclocarbonate terminal groups of the modifier. Thus, these
materials do not comprise a nonisocyanate polyurethane network but
comprise, as a matrix, an epoxy polymer network which immobilizes a
small amount of linear, low-molecular weight nonisocyanate
polyurethane formed from the oligomeric dicyclocarbonate and
aminophenol.
U.S. Pat. No. 5,175,231 to Rappoport et al. discloses the
formation, in a multi-step process, of a network comprising
nonisocyanate polyurethane links in its structure. The disclosed
network is formed from reactions in which a cyclocarbonate is
reacted with an amine and an amine is reacted with an epoxide,
however, the reactants used and the method of network formation are
completely different from the present invention. This patent
discloses that, in a first step, oligomers comprising
cyclocarbonate are formed from epoxide resins. Then, an end-capping
step is carried out in which these oligomers are end-capped with a
diamine, the two amine groups of the diamine reactant having
different reactivity. Finally, the amine end-capped oligomer is
cross-linked by reacting it with an epoxy resin to form a network
structure. In contrast, the present invention differs, inter alia,
by not requiring diamines where the two amine groups of the diamine
have different reactivity, nor does it require that epoxy resins be
used to provide cross-linking.
SUMMARY OF THE INVENTION
One embodiment of the present invention relates to a hybrid
nonisocyanate polyurethane network polymer formed by cross-linking
at least one cyclocarbonate oligomer and at least one amine
oligomer. The cyclocarbonate oligomer contains a plurality of
terminal cyclocarbonate groups. When, for example, a cyclocarbonate
oligomer contains three cyclocarbonate terminal groups, its
functionality is three. In addition to containing a plurality of
terminal cyclocarbonate groups, at least one cyclocarbonate
oligomer further comprises from about 4% to about 12% by weight
(wt. %) of terminal epoxy groups based on the weight of terminal
cyclocarbonate groups present. The cyclocarbonate oligomer or
oligomers have an average functionality towards primary amines of
from about 2.0 to about 5.44. Determination of the average
functionality of the reactants which form the nonisocyanate
polyurethane network is discussed in detail below.
The amine oligomer comprises at least one primary amine-terminated
oligomer terminated with a plurality of primary amine groups and
has an average functionality towards cyclocarbonate groups of from
about 3.0 to about 3.8. The amine oligomer is present in an amount
from about 0.93 to about 0.99 of the amount of the amine oligomer
that would be required to achieve a stoichiometric ratio between
the primary amine groups of the amine oligomer and the
cyclocarbonate groups of the cyclocarbonate oligomer.
Because at least one cyclocarbonate oligomer comprises both
cyclocarbonate and epoxy reactive groups, the network formed
therefrom is referred to as a hybrid nonisocyanate polyurethane
network. The hybrid nonisocyanate polyurethane network polymer
formed has a gel fraction, i.e., the weight fraction of insoluble
material, of not less than about 0.96.
In another embodiment, the invention relates to a method of
producing a network nonisocyanate polyurethane polymer which
comprises:
(a) selecting least one oligomer terminated with a plurality of
cyclocarbonate groups, the cyclocarbonate-terminated oligomer
further comprising from about 4% to about 12% by weight of terminal
epoxy groups based on the weight of terminal cyclocarbonate groups
present, where the oligomer has an average functionality towards
primary amines of from about 2.0 to about 5.44;
(b) selecting at least one other oligomer terminated with a
plurality of primary amine groups, where the amine oligomer has an
average functionality towards cyclocarbonate groups of from about
3.0 to about 3.8;
(c) mixing the oligomers in an amount to form a mixture with a pot
life such that the amount of the amine oligomer(s) present is from
about 0.93 to about 0.99 of the amount of the amine oligomer(s)
that would be required to achieve a stoichiometric ratio between
the primary amine groups of the amine oligomer(s) and the
cyclocarbonate groups of the cyclocarbonate-terminated oligomer(s);
and
(d) curing the mixture at a temperature of from about 10.degree. C.
to about 140.degree. C. to form a hybrid nonisocyanate polyurethane
network polymer with a gel fraction of not less than about 0.96 by
weight.
A further embodiment of the present invention is directed to a
composite material comprising a matrix and a reinforcement, where
the hybrid nonisocyanate polyurethane network is present in the
matrix of the composite. The reinforcement of the composite may be
at least one fiber reinforcement, at least one particulate
reinforcement, or mixtures thereof.
The present invention is also directed to an additional embodiment
where the already good chemical resistance of a nonisocyanate
polyurethane network is increased even further by adding a
particulate, such as an inorganic powder known as an active filler,
along with the oligomeric mixture being fabricated into the network
to form a particulate reinforced composite, where the active filler
comprises the particulate reinforcement and the hybrid
nonisocyanate polyurethane network comprises the matrix of the
composite.
DETAILED DESCRIPTION OF THE INVENTION
Nonisocyanate polyurethane networks are formed from the reaction
between a cyclocarbonate reactant, which typically is an oligomer
or a mixture of oligomers comprising terminal cyclocarbonate
groups, and at least one primary diamine and/or polyamine, which
typically is an oligomer or a mixture of oligomers comprising
terminal primary amine groups. Within this structure, an
intramolecular hydrogen bond is thought to form which is able to
raise the hydrolytic stability of the nonisocyanate polyurethane.
Generally, materials containing intramolecular hydrogen bonds have
chemical resistance from 1.5 to 2 times greater than materials of
similar chemical structure but without such bonds.
Nonisocyanate polyurethane networks exhibit superior resistance
properties to chemical degradation, from 30% to 50% greater than
conventional polyurethanes. Nonisocyanate polyurethane networks
also have significantly reduced permeability, from 3 to 4 times
less than conventional polyurethanes. Unlike conventional
polyurethanes that have a porous structure, nonisocyanate
polyurethane networks form a material substantially free of pores
because, during their formation, they are not sensitive to moisture
on surfaces or fillers. Since they are not formed from highly toxic
isocyanate compounds, nonisocyanate polyurethanes can be easily and
safely synthesized with material hardening commonly occurring at
room temperature.
A mechanism by which the hydrolytic stability is raised is thought
to involve hydrogen bond formation through the introduction, into
the nonisocyanate polyurethane network, of hydroxy groups adjacent
to the urethane carbonyl groups. Network nonisocyanate
polyurethanes are formed from the reaction of a cyclocarbonate
group and a primary amine group to form a urethane link. Without
limitation to any particular theory, after the urethane-forming
reaction occurs, an intramolecular hydrogen bond is thought to be
formed between the urethane carbonyl oxygen and the hydroxy group
at the .beta.-carbon atom of the urethane link to form a 7-member
ring structure as illustrated below: ##STR1## In such systems, a
stabilizing effect is thought to occur because of the
redistribution of charges which arises from the formation of
tautomeric resonance structures. Quantum-mechanical calculations
and IR and NMR spectroscopic investigations reported in the
technical literature affirm the stability of such a ring. [See O.
L. Figovsky, "Improving the Protective Properties of Nonmetallic
Corrosion-Resistant Materials and Coatings", J. Mendeleev Chem.
Soc., 33(3):31-36 (1988).]
The "blockage" of the carbonyl oxygen by hydrogen bonding
considerably lowers the susceptibility of the entire urethane group
to hydrolysis. Moreover, materials containing intramolecular
hydrogen bonds display chemical resistance to aqueous solutions of
acids and alkalies from 1.5 to 2 times greater than materials of
similar chemical structure without such bonds. For example, the
chemical resistance of adhesives based on nonisocyanate
polyurethane materials containing intramolecular hydrogen bonds is
increased over conventional polyurethane network adhesives of
similar chemical structure lacking such bonds.
The present invention uses cyclocarbonate oligomers and primary
amine oligomers as reactants for forming hybrid nonisocyanate
polyurethane networks. Cyclocarbonate oligomers may be formed, for
example, by bubbling carbon dioxide through liquid epoxy oligomers
in the presence of a catalyst, by reacting oligomeric chlorohydrin
ethers with carbonates of alkaline metals, or by reacting
oligomeric polyols with an acid chloride of carbonic acid.
Exemplary cyclocarbonate oligomers include but are not limited to
those shown below as structures (I) and (II): ##STR2## where
m.sub.1, m.sub.2 and m.sub.3 are independently selected over the
range from 3 to 12 inclusive and 0.ltoreq.n.ltoreq.6; and ##STR3##
where 0.ltoreq.n.ltoreq.4. Specially synthesized oligomeric
cyclocarbonates, some examples of which will be described in detail
in Example 1, may also be used.
In general, materials with multiple hydroxy or epoxy groups, such
as commercial triols and triepoxides, may be used as starting
materials for the formation of cyclocarbonate oligomers. These
starting materials typically contain, as their backbones,
polypropylene ethers, polyesters, alkyds, polybutadiene,
polyisoprene, polysiloxane, polyphosphazine, etc.
Polyol starting materials suitable for synthesizing cyclocarbonate
oligomers useful in the present invention are well known to those
in the art and include but are not limited to trimethylolethane,
trimethylolpropane, ditrimethylolpropane, pentaerythritol,
dipentaerythritol, tripentaerythritol and the other polyols
described in further detail in the "Kirk-Othmer Encyclopedia of
Chemical Technology", 4th Ed., Vol. 1, pp. 913-925 (1991) which is
incorporated herein by reference.
Epoxy starting materials suitable for use in the present invention
are well known to those in the art and include but are not limited
to epoxy cresol-novolak resins, epoxy phenol-novolak resins,
polynuclear phenol-glycidyl ether-derived resins, triglycidyl
p-aminophenol-derived resins, triazine-based resins, aliphatic
glycidyl ethers and the other polyfunctional epoxides described in
further detail in the "Kirk-Othmer Encyclopedia of Chemical
Technology", 4th Ed., Vol. 9, pp. 730-755 (1994) which is
incorporated herein by reference.
Well known synthetic methods for converting epoxides into
cyclocarbonates, for example, those disclosed in U.S. Pat. No.
5,340,889 to Crawford et al., can be readily adapted for converting
such materials into cyclocarbonate oligomers suitable for use in
the present invention.
The exemplary cyclocarbonate oligomers shown in (I) and (II) above
comprise only terminal cyclocarbonate (hereafter "CC") groups.
While not shown in (I) and (II) above, it is essential for the
successful implementation of the invention that some portion of the
cyclocarbonate oligomer component also comprise at least one
terminal epoxy (hereafter "EP") functional group. For example, in
(II) for n=1, one of the three terminal cyclocarbonate functional
groups can be replaced by a terminal epoxide group to yield a
so-called epoxy modified cyclocarbonate oligomer. Such a molecule
therefore comprises two CC groups and one EP group. Therefore, it
will be understood that the term "cyclocarbonate oligomer" as used
herein includes molecules comprising only cyclocarbonate terminal
groups and molecules comprising both terminal cyclocarbonate groups
and a terminal epoxy group or groups. Thus, network polymers formed
from such epoxy comprising oligomers are sometimes referred to as
hybrid nonisocyanate polyurethane network polymers to distinguish
them from nonisocyanate polyurethane networks formed only by the
reaction of cyclocarbonate and amine terminal groups. As used
herein, the terms hybrid nonisocyanate polyurethane network and
nonisocyanate polyurethane network are synonymous.
The synthesis of an epoxy modified cyclocarbonate oligomer can
readily be accomplished, for example, by bubbling less than the
stoichiometric amount of carbon dioxide through the liquid epoxy
oligomer precursor of (II) in the presence of a catalyst. Thusly,
only a portion of the epoxy groups in the precursor are converted
to cyclocarbonate groups.
It is thought that the reaction between EP and amine groups occurs
preferentially during the early stages of network formation over
the reaction between CC and amine groups. Thus, oligomers
comprising two, or more, EP groups might react with a diamine
component of the amine terminated oligomer to form a linear polymer
which, when entangled by the later-forming network, forms a
clathrate. Were a clathrate to form, the overall network produced
would be inhomogeneous. Inhomogeneity is thought to be undesirable
because it may lead to a deterioration of network properties, e.g.,
mechanical properties. Therefore, it is preferred that
substantially no cyclocarbonate oligomer comprise two, or more, EP
groups per molecule so that the possibility of forming a linear
polymer between a diepoxide and a diamine is eliminated.
The terminal EP groups of the cyclocarbonate oligomer may be bonded
to a primary carbon atom of the oligomer, i.e., a carbon atom with
two hydrogen substituents, as illustrated in structure (III):
##STR4## wherein R.sub.1 and R.sub.2 are hydrogen and X is the
remainder of the cyclocarbonate oligomer. Alternatively, the carbon
atom adjacent to the EP group may be secondary, i.e., only one of
R.sub.1 and R.sub.2 is hydrogen, or tertiary, i.e., neither one of
R.sub.1 and R.sub.2 is hydrogen. Preferably, when the
cyclocarbonate oligomer comprises a terminal EP group, the EP group
is bonded to the remainder of the cyclocarbonate oligomer by at
least one primary carbon atom adjacent to the EP group.
The desired CC:EP weight ratio of the cyclocarbonate reactant
ranges from about 1:0.04 to about 1:0.12, i.e., from about 4% to
about 12% by weight of terminal epoxy groups based on the weight of
terminal cyclocarbonate groups present in the cyclocarbonate
reactant. Cyclocarbonate reactants comprising terminal epoxy groups
present within this range are preferred, e.g., because the networks
prepared therefrom have good resistance to hydrolysis. If the
amount of EP groups is too low, i.e., less than about 4 wt. %, the
nonisocyanate polyurethane network resulting therefrom generally
has poor tensile strength. If the amount of EP groups is too high,
i.e., greater than about 12 wt. %, the nonisocyanate polyurethane
network resulting therefrom is generally brittle and has an
ultimate elongation which is too low. By using mixtures of
different cyclocarbonate oligomers, e.g., at least one
cyclocarbonate oligomer comprising a terminal EP group and at least
one other cyclocarbonate oligomer comprising only terminal CC
groups, it is possible to prepare cyclocarbonate oligomer
compositions with the desired CC:EP weight ratio.
Each terminal primary amine group may react with only one terminal
cyclocarbonate group to form, for example, a structure labeled as
(IV) in the figure below: ##STR5## wherein R.sub.1 represents the
remainder of a cyclocarbonate oligomer and R.sub.2 represents the
remainder of a primary amine oligomer. Without limitation, the
remaining hydrogen attached to the urethane nitrogen atom is
thought to be substantially unreactive because of steric
hindrance.
However, each terminal primary amine group may react with up to two
terminal epoxy groups to form, for example, a structure labeled as
(V) in the figure below: ##STR6##
where each primary amine of a diamine oligomer is shown to be
reacted with two epoxy groups, and where R.sub.3 represents the
remainder of four cyclocarbonate oligomers comprising a terminal
epoxy group, each of which may be different from or identical to
any of the other above-represented cyclocarbonate oligomers, and
R.sub.4 represents the remainder of a primary diamine oligomer.
Therefore, in determining the average functionality of the
cyclocarbonate oligomer towards the primary amine oligomer, the
difference in the reactivity of the cyclocarbonate and the epoxy
groups must be taken into account. The mechanism for doing so is
illustrated by the following sample functionality
determinations.
For example, a difunctional cyclocarbonate oligomer wherein the
reactive functional groups, or RFG, comprise 90 wt. % CC groups and
10 wt. % EP groups has a functionality of the cyclocarbonate
oligomer toward a primary amine oligomer of 2.2, which is
determined as follows:
______________________________________ 0.90 CC .times. 2
RFG/molecule .times. 1 CC/amine = 1.8 0.10 EP .times. 2
RFG/molecule .times. 2 EP/amine = 0.4 Functionality = 2.2
______________________________________
For a trifunctional cyclocarbonate oligomer wherein the reactive
functional groups comprise 90 wt. % CC groups and 10 wt. % EP
groups, the functionality of the cyclocarbonate oligomer toward a
primary amine oligomer, 3.3, is determined as follows:
______________________________________ 0.90 CC .times. 3
RFG/molecule .times. 1 CC/amine = 2.7 0.10 EP .times. 3
RFG/molecule .times. 2 EP/amine = 0.6 Functionality = 3.3
______________________________________
For a trifunctional cyclocarbonate oligomer wherein the reactive
functional groups comprise 95 wt. % CC groups and 5 wt. % EP
groups, the functionality of the cyclocarbonate oligomer toward a
primary amine oligomer, 3.15, is determined as follows:
______________________________________ 0.95 CC .times. 3
RFG/molecule .times. 1 CC/amine = 2.85 0.05 EP .times. 3
RFG/molecule .times. 2 EP/amine = 0.30 Functionality = 3.15
______________________________________
By using mixtures of different cyclocarbonate oligomers, it is
possible to prepare cyclocarbonate oligomer compositions with the
desired average functionality toward primary amines, i.e., over the
range of from about 2.0 to about 5.44 and, preferably, from about
2.6 to about 5.3. When a mixture of cyclocarbonate oligomers is
present, any or all of the components of such a mixture may have a
functionality toward primary amine groups less than about 2.0 or
greater than about 5.44, so long as the average functionality of
the mixture falls within the range of from about 2.0 to about 5.44
and, preferably, from about 2.6 to about 5.3.
For example, for a cyclocarbonate oligomer mixture comprising 20
wt. % of a tetrafunctional cyclocarbonate, i.e., functionality of
4.0, and 80 wt. % of a trifunctional cyclocarbonate oligomer
wherein the reactive functional groups comprise 95 wt. % CC groups
and 5 wt. % EP groups, i.e., a functionality of 3.15, the average
functionality of the cyclocarbonate oligomer blend, 3.32, toward a
primary amine oligomer is determined as follows:
______________________________________ 0.20 .times. 4.0
functionality = 0.80 0.80 .times. 3.15 functionality = 2.52 Average
Functionality = 3.32 ______________________________________
Each cyclocarbonate oligomer of the present invention, whether used
alone or in a mixture of such oligomers, typically has a number
average molecular weight of from about 350 g/mol to about 3,200
g/mol and, preferably, from about 700 g/mol to about 1400 g/mol.
Each cyclocarbonate oligomer of the present invention, whether used
alone or in a mixture of such oligomers, typically has a viscosity
at 25.degree. C. of from about 150 mPa.s to about 8,800 mPa.s and,
preferably, from about 350 mPa.s to about 1,500 mPa.s.
Preferred cyclocarbonate oligomers include but are not limited to
the di-, tri-, tetra- and penta-carbonate ester, ether or amine
derivatives of aromatic or aliphatic compounds comprising from 2 to
5 terminal hydroxy and/or amine functional groups and mixtures
thereof, e.g., the materials described in Examples 1-1 through
1-6.
More preferred cyclocarbonate oligomers include but are not limited
to those described in structures (I) and (II) above and to those
shown as structures (VI), (VII) and (VIII) below: ##STR7##
The amine reactant or reactants used in the present invention are
typically oligomers comprising at least two primary amine groups,
i.e., --NH.sub.2. The terminal amine groups must be primary.
Secondary and tertiary amine groups are not preferred. Exemplary
primary amine oligomers include but are not limited to those shown
below as structures (IX) and (X): ##STR8## where
2.ltoreq.m.ltoreq.12; and ##STR9##
Specially synthesized oligomeric amines, some examples of which
will be described in detail in Example 2, may also be used.
Alternatively, in the network-forming reaction with oligomeric
cyclocarbonates, commercial oligomeric primary amines, such as
polyoxypropylenetriamine (JEFFAMINE.RTM. 403, Texaco Chemical Co.,
believed to have a molecular weight of 400 to 550 g/mol) and
tris-(3-aminopropyl)-cyanurate (BASF AG, Germany) may be used.
The terminal primary amine groups of the amine oligomer may be
bonded to a primary carbon atom of the oligomer, i.e., a carbon
atom with two hydrogen substituents, as illustrated in structure
(XI): ##STR10## wherein R.sub.1 and R.sub.2 are hydrogen and Y is
the remainder of the primary amine oligomer. Alternatively, the
carbon atom adjacent to the primary amine group may be secondary,
i.e., only one of R.sub.1 and R.sub.2 is hydrogen. It is not
desirable for the carbon atom adjacent to the primary amine group
to be tertiary, i.e. , neither one of R.sub.1 and R.sub.2 in
structure (XI) above is hydrogen. Preferably, the primary amine
group is bonded to the remainder of the primary amine oligomer by
at least one primary carbon atom adjacent to the amine group.
More preferably, a terminal primary amine group of the amine
oligomer is bonded to the primary amine oligomer by at least two
linked carbon atoms, where the carbon atom adjacent to the amine is
a primary carbon atom, as illustrated in structure (XII): ##STR11##
wherein Z is the remainder of the primary amine oligomer. The
carbon atom .beta. to the primary amine group may be primary, i.e.,
R.sub.3 and R.sub.4 are hydrogen, secondary or tertiary.
Preferably, the primary amine group is bonded to the remainder of
the primary amine oligomer by at least two linked primary carbon
atoms adjacent to the amine group, i.e., structure (XII) above
where R.sub.3 and R.sub.4 are hydrogen.
The lowest molecular weight aliphatic primary amine oligomer which
is effective in the present invention is 1,2-diaminoethane.
It is not preferred for any primary amine group to be substituted
directly on an aromatic ring or separated from such a ring by only
one carbon atom. Rather, each terminal primary amine group of the
primary amine oligomer should be separated from an aromatic ring by
at least two linked primary carbon atoms, e.g., when Z in structure
(XII) above is aromatic, R.sub.3 and R.sub.4 are hydrogen.
It is not preferred for any primary amine group to be substituted
directly on an aliphatic ring structure. Rather, each primary amine
group should be separated from such a ring by at least one primary
carbon atom and, preferably, by at least two linked primary carbon
atoms.
When the remainder of the primary amine oligomer to which a
terminal primary amine group is to be attached comprises siloxane
groups, e.g., diphenyl-dimethoxysilane as illustrated in detail
below in Example 2-1 or cyclohexyl-methyl-dimethoxysilane as
illustrated in detail below in Example 2-2, it is preferred that
the primary amine be separated from the siloxane by at least three
linked primary carbon atoms.
However, it is not preferred for the amine to be bonded to the
remainder of the primary amine oligomer by a chain of about twelve
or more linked primary carbon atoms. Primary amine oligomers
comprising such structures are thought to be to non-polar and too
difficult to dissolve in the cyclocarbonate oligomer.
As discussed in detail above, each terminal primary amine group may
react with only one terminal cyclocarbonate group. By using
mixtures of primary amines having a different number of terminal
primary amine groups per molecule, e.g., mixtures comprising
diamines, triamines, tetraamines, pentaamines, hexaamines and/or
heptaamines, it is possible to prepare a primary amine oligomer
reactant having an average functionality toward cyclocarbonate
groups over the range of from about 3.0 to about 3.8. When a
mixture of primary amine oligomers is present, any or all of the
components of such a mixture may have a functionality toward
terminal CC groups less than about 3.0 or greater than about 3.8,
so long as the average functionality of the mixture falls within
the range of from about 3.0 to about 3.8.
The mechanism for determining the average functionality of the
primary amine oligomer toward the cyclocarbonate oligomer is
illustrated by the following example determination.
For a primary oligomer mixture comprising 20 wt. % of molecules
with 10 primary amine groups per molecule, e.g., a siloxane, and 80
wt. % diamine, the average functionality of the amine oligomer,
3.6, toward the cyclocarbonate is determined as follows:
______________________________________ 0.20 .times. 10 amines
.times. 1 amine/CC = 2.0 0.80 .times. 2 amines .times. 1 amine/CC =
1.6 Average Functionality = 3.6
______________________________________
Each primary amine oligomer of the present invention, whether used
alone or in a mixture of such oligomers, typically has a number
average molecular weight of from about 60 g/mol to about 3,900
g/mol and, preferably, from about 180 g/mol to about 880 g/mol.
Each primary amine oligomer of the present invention, whether used
alone or in a mixture of such oligomers, typically has a viscosity
at 25.degree. C. of from about 10 mPa.s to about 2,800 mPa.s and,
preferably, from about 50 mPa.s to about 750 mPa.s.
Preferred primary amine oligomers include but are not limited to
aminosilane oligomers with a functionality toward CC of 3 to 7,
e.g., the primary amine oligomer described in Examples 2-1 and 2-2
below; oligovinyl ethers of monoethanolamine with functionality
toward CC of 3 to 8; monomeric triamines, tetraamines and
pentaamines, e.g., tris-(3-aminopropyl)-cyanurate;
polypropylenetriamine; polypropylenepentamine; and mixtures
thereof.
More preferred primary amine oligomers include but are not limited
to polyoxypropylenetriamine, tris-(3-aminopropyl)-cyanurate,
polypropylenetriamine, polypropylenepentamine, those described in
structures (IX) and (X) above and those shown as structure (XIII)
below: ##STR12## where m.sub.1, m.sub.2 and m.sub.3 are
independently selected over the range from 3 to 12 inclusive and
1.ltoreq.n.ltoreq.3.
In forming the nonisocyanate polyurethane networks of the present
invention, it is not preferable to have a stoichiometric amount of
the cyclocarbonate oligomer react with the primary amine oligomer,
e.g., a 1:1 stoichiometric ratio of terminal functional groups such
that each CC group has one primary amine group available to react
with it. Rather, it is preferable to have an excess of
cyclocarbonate groups. The preferred amount of each oligomer
present is such that the weight ratio of the amine oligomer or
oligomers to the cyclocarbonate oligomer or oligomers is from about
0.93 to about 0.99 of the stoichiometric ratio, known hereafter as
the "departure from the stoichiometric ratio of amine oligomer to
cyclocarbonate oligomer".
The method of mixing the reactants is not critical to the success
of forming the nonisocyanate polyurethane networks of the present
invention. The components may be, but need not be, mixed under
reduced pressure, e.g., from under atmospheric pressure, i.e., less
than about 1 atm, to about 0.001 atm, to facilitate the removal of
gases during mixing as is known to those with skill in the art. No
catalyst is required for the reaction between the primary amine
groups and the cyclocarbonate and epoxy groups to take place. No
solvent is required to facilitate the reaction. However, catalysts
and/or solvents may be used, if desired, as known to one skilled in
the polymerization art.
The reaction of cyclocarbonate groups and diamine groups is not
highly exothermic, thus, the rate of this reaction is not
particularly sensitive to reaction temperature. In general, the
reaction may be carried out over a temperature range of from about
10.degree. C. to about 140.degree. C. and, preferably, from about
15.degree. C. to about 30.degree. C. In general, the reaction may
be carried out over a pressure range of from about 1 atm to about
10 atm, preferably, from about 2 atm to about 10 atm and, more
preferably, from about 3 atm to about 5 atm. The pot life is at
least about 15 minutes and, typically, is at least about 2 hours at
25.degree. C. Since primary amine groups are reactive with air,
normal precautions familiar to the skilled artisan, such as
blanketing with nitrogen or an inert gas, should be taken during
the synthesis of the primary amine oligomers and their handling
during the formation of the nonisocyanate polyurethane networks of
the present invention.
If desired, in addition to the cyclocarbonate oligomer(s) and the
primary amine oligomer(s), the nonisocyanate polyurethane network
can also comprise further components, examples being solvents,
pigments, dyes, plasticizers, stabilizers, fillers, including
active fillers which will be discussed in detail below,
microspheres, reinforcing agents, for example fibers in the form of
filaments, staple, mats, etc., which will be discussed in more
detail below, thixotropic agents, coupling agents, catalysts and/or
leveling agents. Examples of possible components are those
described in Ullmann's Encyclopedia of Industrial Chemistry, 5th
Edition, Vol. A18, pp. 429-471, VCH Verlagsgesellschaft, Weinheim
1991 which is incorporated herein by reference.
The amount of cross-linking in a nonisocyanate polyurethane network
polymer is readily determined, e.g., by conducting a gel fraction
test. The cross-linked fraction of the network, being of extremely
high molecular weight, does not dissolve in some solvents while the
non-cross-linked, lower molecular weight fraction does dissolve.
Therefore, as is well known to those skilled in this art, the
weight fraction of cross-linked material, or gel fraction, can be
determined by weighing a sample of the nonisocyanate polyurethane
network, dissolving out the non-cross-linked portion, and then
filtering, drying and weighing the undissolved portion.
Typically, the nonisocyanate polyurethane network polymer formed
has a gel fraction, i.e., the weight fraction of insoluble
material, of not less than about 0.96. Preferably, the
nonisocyanate polyurethane network
polymer formed from the cyclocarbonate oligomer and the primary
amine oligomer has a gel fraction of not less than about 0.975 and,
more preferably, of not less than about 0.980.
Without limitation to any particular theory, it is believed the
presence of more than about 4% of linear nonisocyanate polyurethane
polymer with the network results in a gel fraction below about 0.96
and in a deterioration of the properties of the network, e.g., the
mechanical properties such as tensile strength.
In a further embodiment of the present invention, the matrix of a
composite material comprises a nonisocyanate polyurethane network
of the present invention, these networks being characterized in
detail above. Composites are generally described as a macroscopic
combination of two or more components. One of the components of the
composite is typically a fiber or a particulate, although fibers
and particulates may both be present, and is used to reinforce the
composite; therefore, this component is referred to herein as the
reinforcement. The other component of the composite typically
surrounds the fiber or particulate and is generally referred to as
the matrix. In the composites of the present invention, the matrix
comprises a nonisocyanate polyurethane network polymer.
Fibrous reinforcements useful in the composites of the present
invention include but are not limited to glass fibers, such as
E-glass and S-glass; carbon fibers, such as intermediate modulus
polyacrylonitrile (PAN)-based intermediate modulus fibers, very
high strength fibers (VHS), ultrahigh modulus fibers (UHM) and
graphite fibers; aramid fibers, such as KEVLAR.RTM. 29 and
KEVLAR.RTM. 49; boron fibers; polyethylene fibers; basalt fibers;
ceramic fibers; silicon carbide fibers; and mixtures thereof. The
fibrous reinforcement may be present in a variety of forms, for
example, as short, discontinuous fibers randomly arranged, as
continuous filaments arranged with their axis parallel to one
another, as bundled continuous filaments also known as woven
rovings, or as braids. Alternatively, two or more such arrangements
of fibers may be used and oriented with their long axis parallel,
perpendicular, or at some intermediate angle to each other. Such
fibrous reinforcements and their arrangements are described in
further detail in the "Kirk-Othmer Encyclopedia of Chemical
Technology", 4th Ed., Vol. 7, pp. 1-60 (1993) which is incorporated
herein by reference.
Preferred fibrous reinforcements useful in the composites of the
present invention include glass, carbon and basalt fibers.
Preferably, the nonisocyanate polyurethane network matrix is
present in an amount of from about 12 wt. % to about 45 wt. %,
based on the total weight of the composite, and the fiber
reinforcement is present in an amount of from about 55 wt. % to
about 85 wt. % in a fiber reinforced composite of the present
invention.
The present invention is also directed to an embodiment wherein the
already good chemical resistance of a nonisocyanate polyurethane
network is increased even further by adding a particulate, such as
an inorganic powder known as an active filler, along with the
oligomeric mixture being fabricated into the network. Such a
structure is also known as a particulate reinforced composite,
where the active filler comprises the particulate and the
nonisocyanate polyurethane network comprises the matrix.
Preferred active fillers are believed to selectively interact with
an aggressive medium, e.g., acids, alkalis and/or salts, their
aqueous solutions, and/or water to form a system of high-strength
hydrate complexes. Such additives compliment formulations
comprising nonisocyanate polyurethane networks, such as adhesives,
and result in high-strength, durable inorganic filled composite
adhesive cements.
Without limitation to any particular theory, it is believed that,
as the active filler interacts with water or with the aggressive
medium, hydrate complexes, also known as crystal-hydrates, form in
the defects, e.g., micropores and/or microcracks, of the
formulation. This process acts to "repair" these defects and
thereby to increase the strength of the formulation. Additionally,
active fillers are thought to function as barriers which inhibit
the further penetration of aggressive media. Moreover, as the
crystal-hydrates are formed, the volume and the specific surface
area of the active filler increases. As a direct result of the
increased specific surface area of the active filler, the adhesion
between the filler and the nonisocyanate polyurethane is believed
to become even stronger.
Active fillers include but are not limited to metal oxides and the
metal aluminate salts, i.e., compounds having the formula:
wherein M is a metal ion and v is the valency of the metal, with
metal aluminate salts being preferred. Preferred metals, all with a
valency of 2 except where indicated in parenthesis, include Cu, Ca,
Pb, Mg, Zn, Fe(3) and mixtures thereof. More preferred as active
fillers are copper aluminate, calcium aluminate, lead aluminate and
mixtures thereof. Even more preferred as active fillers are copper
aluminate, calcium aluminate and mixtures thereof. The most
preferred active filler, copper aluminate, is available
commercially from Sigma Chemical and Alfa-Aesar.
An active filler can be used with any of the nonisocyanate
polyurethane network compositions of the invention. The method of
mixing the reactants with the active filler is not critical to the
success of forming a composite from a nonisocyanate polyurethane
network of the present invention. Preferably, however, the active
filler is added to one reactant component before the cross-linking
reaction begins. The mean particle size, e.g., diameter, of the
active filler is not critical to the success of the invention,
provided that it is less than or equal to about 30 .mu.m. The mean
particle diameter of the active filler typically ranges from about
2.5 .mu.m to about 30 .mu.m and, preferably, from about 4.5 .mu.m
to about 15 .mu.m.
When increased resistance to an aggressive medium is desired, the
active filler is typically present in an amount of from about 3
parts to about 200 parts by weight based on 100 parts of
nonisocyanate polyurethane network. Preferably, from about 10 parts
to about 100 parts by weight and, more preferably, from about 20
parts to about 40 parts by weight of the active filler is present
in the nonisocyanate polyurethane network.
EXAMPLES
The following examples of oligomers and hybrid nonisocyanate
polyurethane networks formed in accordance with the present
invention are given to illustrate the present invention. However,
it is to be understood that the examples are for illustrative
purposes only and in no manner is the present invention limited to
the specific disclosures therein.
A molecular weight of 101 g/mol was used in calculating the wt. %
of terminal cyclocarbonate groups of a cyclocarbonate oligomer.
This molecular weight is arrived at by combining the molecular
weight of a cyclocarbonate group, 87 g/mol, and the molecular
weight of a --CH.sub.2 -- unit connecting the cyclocarbonate group
to the remainder of the cyclocarbonate oligomer. Thus, for purposes
of such calculations in this application, a terminal cyclocarbonate
group has a molecular weight of 101 g/mol and a molecular formula
of C.sub.4 H.sub.5 O.sub.3.
A molecular weight of 57 g/mol was used in calculating the wt. % of
terminal epoxy groups of a cyclocarbonate oligomer. This molecular
weight is arrived at by combining the molecular weight of an epoxy
group, 43 g/mol, and the molecular weight of a --CH.sub.2 -- unit
connecting the epoxy group to the remainder of the cyclocarbonate
oligomer. Thus, for purposes of such calculations in this
application, a terminal epoxy group has a molecular weight of 57
g/mol and a molecular formula of C.sub.3 H.sub.5 O.
A molecular weight of 30 g/mol was used in calculating the wt. % of
terminal primary amine groups of a primary amine oligomer. This
molecular weight is arrived at by combining the molecular weight of
a primary amine group, 16 g/mol, and the molecular weight of a
--CH.sub.2 -- unit connecting the primary amine group to the
remainder of the primary amine oligomer. Thus, for purposes of such
calculations in this application, a terminal primary amine group
has a molecular weight of 30 g/mol and a molecular formula of
CH.sub.4 N.
Example 1
Synthesis of Cyclocarbonate Oligomers
Example 1-1
To the glycidyl ether of diaminophenol known as ARALDITE.RTM. MY
0510 (Ciba Geigy AG, Switzerland) was added 0.7% by weight of
tetraethyl ammonium chloride. The mixture was placed in a
wiped-film still (Pope Scientific, Inc.) and heated to 95.degree.
C. Carbon dioxide gas was bubbled through the mixture for 190
minutes at a pressure of 7.5 atm. IR spectroscopy indicated that
the synthesized oligomer had 45.4 wt. % of cyclocarbonate groups
and 2.9 wt. % of epoxy groups. Thus, the weight ratio of
cyclocarbonate groups:epoxy groups was 1:0.064. The molecular
weight of the cyclocarbonate oligomer was 666 g/mol and its
functionality, as determined by its reactivity toward primary
amines, was 3.17.
Example 1-2
To the triglycidyl ether of oligoepichlorohydrintriol known as
OXILIN.RTM. 6a (SIAC, Russia) was added 0.45% by weight of
tetramethyliodide of ammonium. The mixture was placed in a
wiped-film still and heated to 65.degree. C. Carbon dioxide gas was
bubbled through the mixture for 280 minutes at a pressure of 8 atm.
IR spectroscopy indicated that the synthesized oligomer had 17.2
wt. % of cyclocarbonate groups and 1.9 wt. % of epoxy groups. Thus,
the weight ratio of cyclocarbonate groups:epoxy groups was 1:0.11.
The molecular weight of the cyclocarbonate oligomer was 1668 g/mol
and its functionality was 2.9.
Example 1-3
To the glycidyl ether of 4,4'-diaminodiphenylmethane known as
ARALDITE.RTM. MY 720 (Ciba Geigy AG) was added 0.35% by weight of
hydrazine hydrochloride. The mixture was placed in a wiped-film
still and heated to 105.degree. C. Carbon dioxide gas was bubbled
through the mixture for 290 minutes at a pressure of 8.5 atm. IR
spectroscopy indicated that the synthesized oligomer had 24.9 wt. %
of cyclocarbonate groups and 3.3 wt. % of epoxy groups. Thus, the
weight ratio of cyclocarbonate groups:epoxy groups was 1:0.13. The
molecular weight of the cyclocarbonate oligomer was 1124 g/mol and
its functionality was 4.2.
Example 1-4
To the glycidyl ether of neopentyldiol known as XD-7114 (Dow
Chemical Co.) was added 0.55% by weight of hydrazine hydrobromide.
The mixture was placed in a wiped-film still and heated to
70.degree. C. Carbon dioxide gas was bubbled through the mixture
for 200 minutes at a pressure of 6.0 atm. IR spectroscopy indicated
that the synthesized oligomer had 43.6 wt. % of cyclocarbonate
groups and 1.4 wt. % of epoxy groups. Thus, the weight ratio of
cyclocarbonate groups:epoxy groups was 1:0.032. The molecular
weight of the cyclocarbonate oligomer was 480 g/mol and its
functionality was 2.05.
Example 1-5
To the pentaglycidic ester of oligooxypropylenepentol known as
LAPROXID.RTM. 805 (Makromer, Russia) was added 0.65% by weight of
tetraethyl ammonium chloride. The mixture was placed in a
wiped-film still and heated to 90.degree. C. Carbon dioxide gas was
bubbled through the mixture for 300 minutes at a pressure of 7.5
atm. IR spectroscopy indicated that the synthesized oligomer had
37.8 wt. % of cyclocarbonate groups and 3.6 wt. % of epoxy groups.
Thus, the weight ratio of cyclocarbonate groups:epoxy groups was
1:0.096. The molecular weight of the cyclocarbonate oligomer was
1285 g/mol and its functionality was 5.44.
Example 1-6
To the glycidyl ether of bisphenol F known as ARALDITE.RTM. PY 306
(Ciba Geigy AG) was added 0.4% by weight of tetramethyliodide of
ammonium. The mixture was placed in a wiped-film still and heated
to 75.degree. C. Carbon dioxide gas was bubbled through the mixture
for 210 minutes at a pressure of 9.5 atm. IR spectroscopy indicated
that the synthesized oligomer had 29.4 wt. % of cyclocarbonate
groups and 2.2 wt. % of epoxy groups. Thus, the weight ratio of
cyclocarbonate groups:epoxy groups was 1:0.076. The molecular
weight of the cyclocarbonate oligomer was 591 g/mol and its
functionality was 2.07.
Example 2
Synthesis of Primary Amine Oligomers
Example 2-1
53.6 g 3-aminopropyl-triethoxysilane (Huls AG, Germany) was mixed
with 39.6 g of diphenyl-dimethoxysilane (Huls AG) and 6.6 g of
water in a stirred reactor. After 5 hours of mixing at 20.degree.
C., ethanol and methanol were vacuum distilled off. The product
amine oligomer had a functionality of 5.98, as determined by its
reactivity toward cyclocarbonate groups, and a molecular weight of
2190 g/mol.
Example 2-2
59.2 g 3-aminopropyl-triethoxysilane (Huls AG) was mixed with 33.6
g of cyclohexyl-methyl-dimethoxysilane (Huls AG) and 7.2 g water in
a stirred reactor. After 6 hours of mixing at 20.degree. C., the
alcohols were vacuum distilled off. The product amine oligomer had
a functionality of 5.96 and a molecular weight of 1970 g/mol.
Example 2-3
270.5 g of diglycidyl-1,1-bis(dioxymethyl)-3,4-epoxycyclohexane
(known as resin "UP-65OT", obtained from the experimental plant of
the Plastic Research Institute, Donetzk, Ukraine) was mixed with
216.0 g of 1,4-butylenediamine in a stirred reactor and mixed for 4
hours at 65.degree. C. The product amine oligomer had a
functionality of 2.93 and a molecular weight of 505 g/mol.
Example 3
Preparation of a Hybrid Network Nonisocyanate Polyurethane
The cyclocarbonate oligomers of Examples 1-1 and 1-2 were mixed in
a ratio of 1:0.8 respectively by weight (55.6 g of 1-1 and 44.4 g
of 1-2) for 5 minutes at 20.degree. C. in a low velocity mixer.
This oligomer mixture, component "A", had an average functionality
(determined by its reactivity toward primary amine groups) of 3.05,
32.8 wt. % of cyclocarbonate terminal groups and 2.4 wt. % of epoxy
terminal groups. Thus, the weight ratio of cyclocarbonate
groups:epoxy groups was 1:0.073.
Polyoxypropylenetriamine, known as JEFFAMINE.RTM. 403 and with a
functionality of 2.98 as determined by its reactivity toward
cyclocarbonate groups, and the amine oligomer of Example 2-2 were
mixed in a ratio of 1:0.2 respectively by weight (72.05 g of
polyoxypropylenetriamine and 14.45 g of 2-2) for 5 minutes at
20.degree. C. in a low velocity mixer. This mixture of such amines,
component "B", had an average functionality (determined by its
reactivity toward cyclocarbonate groups) of 3.475.
The stoichiometric ratio for mixing the CC groups of the
above-described A component with the primary amine groups of the
above-described B component, B:A, was calculated to be 0.878:1,
i.e., 87.8 g of B per 100 g of A. This ratio was determined by
dividing the average functionality of component A by the average
functionality of component B, i.e., 3.05/3.475. An excess of
cyclocarbonate groups was assured by mixing only 86.5 g of B with
100 g of A, i.e., a B:A ratio of 0.865:1. Therefore, the actual B:A
ratio of 0.865:1 differs from the stoichiometric B:A ratio of
0.878:1, being 98.5% of the latter. Thus, the departure from the
stoichiometric ratio of amine oligomer to cyclocarbonate oligomer
is 0.985.
The A and B components were mixed at a B:A ratio of 0.865:1 for 15
minutes at 20.degree. C. in a low velocity mixer. The particular
method of mixing is not critical to the success of the reaction.
The mixture was then poured out and allowed to cross-link or cure
for 10 days at the 20.degree. C. The resulting network polymer had
an intermolecular distance, as characterized by the number average
molecular weight, of 882 g/mol and contained 0.987 by weight of
gel. According to IR analysis, the post-reaction weight ratio of
reacted CC groups to reacted EP groups was 1:0.08 (31.7 wt. %
CC:2.5 wt. % EP).
Example 4
Hybrid Nonisocyanate Polyurethane Network Compositions and
Properties
Using both the oligomers synthesized in the examples above and
commercially available reactants, sample nonisocyanate polyurethane
network compositions were prepared with various ratios of
cyclocarbonate terminal groups to epoxy terminal groups, with
various average functionalities of amine oligomer components, with
various average functionalities of the cyclocarbonate oligomer
components, and with various departures from the stoichiometric
ratio of amine oligomer to cyclocarbonate oligomer components.
These sample compositions have the chemical compositions and
physical properties shown in Tables 1 and 2.
The tensile properties were determined according to the method
prescribed by ASTM D 638-84.
The gel fraction was determined by taking a 5 to 10 g sample of
each network formed, weighing it, wrapping it with filter paper and
placing the sample into a Soxhlet extraction apparatus. Each sample
was extracted with a boiling mixture of 20% ethyl alcohol/80%
toluene until it reached constant weight, generally in 3 to 7 days.
The gel fraction was determined by dividing the final weight by the
initial eight.
TABLE 1
__________________________________________________________________________
Compositions and Properties of Hybrid Nonisocyanate Polyurethane
Networks SAMPLE NO. 1C 2C 3 4 5 6 7 8 9C 10C
__________________________________________________________________________
COMPOSITION Weight Ratio of CC:EP 1:0.03 1:0.04 1:0.08 1:0.12
1:0.13 Average Functionality of Oligomers: Amine 3.0 3.8 3.0 3.8
3.0 3.8 3.0 3.8 3.0 3.8 Cyclocarbonate 5.3 2.6 5.3 2.6 5.3 2.6 5.3
2.6 5.3 2.6 Departure from Stoichiometric 0.93 0.93 0.93 0.93 0.98
0.98 0.97 0.97 0.97 0.97 Ratio of Amine Oligomer/Cyclocarbonate
Oligomer PROPERTIES Tensile Strength (.sigma.), MPa 38.3 32.7 42.3
39.0 44.1 39.2 49.0 39.7 44.3 38.6 Ultimate Elongation (.epsilon.),
% 40.1 50.4 41.5 59.8 40.7 55.8 40.6 54.6 32.0 42.3 Gel-Fraction,
by weight 0.960 0.975 0.990 0.985 0.980 0.980 0.985 0.980 0.970
0.965 Specific Energy of Failure, 1.54 1.65 1.76 2.33 1.79 2.19
1.99 2.17 1.42 1.63 .sigma. .times. .epsilon. .times. 10.sup.-3
__________________________________________________________________________
TABLE 2
__________________________________________________________________________
Compositions and Properties of Hybrid Nonisocyanate Polyurethane
Networks SAMPLE NO. 11C 12 13C 14C 15 16C 17C 18 19 20C
__________________________________________________________________________
COMPOSITION Weight Ratio of CC:EP 1:0.04 1:0.08 1:0.12 Average
Functionality of Oligomers: Amine 2.9 3.5 3.9 2.9 3.2 3.9 2.8 3.0
3.8 3.9 Cyclocarbonate 5.4 3.0 2.5 5.4 3.3 2.5 5.4 5.3 2.6 3.4
Departure from Stoichiometric 0.93 0.93 0.93 0.98 0.98 0.98 0.97
0.97 0.97 0.97 Ratio of Amine Oligomer/Cyclocarbonate Oligomer
PROPERTIES Tensile Strength (.rho.), MPa 30.7 43.6 31.8 30.9 47.5
32.6 39.8 45.0 39.7 30.9 Ultimate Elongation (.epsilon.), % 42.9
58.7 50.5 40.7 49.2 41.0 37.5 40.6 54.6 40.1 Gel-Fraction, by
weight 0.960 0.990 0.970 0.970 0.985 0.970 0.965 0.985 0.980 0.955
Specific Energy of Failure, 1.32 2.56 1.61 1.,26 2.34 1.34 1.49
1.83 2.17 1.24 .rho. .times. .epsilon. .times. 10.sup.-3
__________________________________________________________________________
It is apparent from the results presented in Tables 1 and 2 that,
in general, the hybrid nonisocyanate polyurethane networks of the
present invention, i.e., Sample Nos. 3-8, 12, 15, 18 and 19, have
good mechanical properties as demonstrated by their tensile
strengths, ultimate elongations and specific energies of
failure.
On the other hand, it is apparent that if the weight ratio of CC:EP
groups is too low, i.e., below about 1:0.04 or below about 4 wt. %
EP, the properties of the network are degraded. For example, for
Sample Nos. 1C and 2C of Table 1 with a CC:EP weight ratio of
1:0.03, the tensile strength and specific energy of failure are
lower than the corresponding values for any of the samples of the
invention, i.e., Sample Nos. 3-8.
Additionally, if the weight ratio of CC:EP groups is too high,
i.e., above about 1:0.12 or above about 12 wt. % EP, the properties
of the network are also degraded. For example, for Sample No. 9C of
Table 1 with a CC:EP weight ratio of 1:0.13, the ultimate
elongation and specific energy of failure are lower than the
corresponding values for any of the samples of the invention, i.e.,
Sample Nos. 3-8. For the other sample of Table 1 with a CC:EP
weight ratio of 1:0.13, Sample No. 10C, the tensile strength and
specific energy of failure are lower than the corresponding values
for any of the samples of the invention.
If the average functionality of the primary amine oligomer toward
terminal cyclocarbonate groups is too high, i.e., above about 3.8,
the properties of the network are degraded. For example, for Sample
Nos. 13C, 16C and 20C of Table 2, all with an amine average
functionality value of 3.9, the tensile strength and specific
energy of failure are lower than the corresponding values for any
of the samples of the invention, i.e., Sample Nos. 12, 15, 18 and
19.
On the other hand, if the average functionality of the primary
amine oligomer toward terminal cyclocarbonate groups is too low,
i.e., below about 3.0, the properties of the network are also
degraded. For example, for Sample Nos. 11C and 14C of Table 2, both
with an amine average functionality value of 2.9, the tensile
strength and specific energy of failure are lower than the
corresponding values for any of the samples of the invention, i.e.,
Sample Nos. 12, 15, 18 and 19. Similarly, for the other sample of
Table 2 with a low amine average functionality value, 2.8 for
Sample No. 17C, the ultimate elongation and specific energy of
failure are lower than the corresponding values for any of the
samples of the invention.
Additionally, if the gel fraction is too low, i.e., below about
0.96, the
properties of the network are degraded. For example, Sample No.
20C, with a gel fraction of 0.955 and a specific energy of failure
of 1.24, has the lowest specific energy of failure for any of the
samples present in Tables 1 and 2.
Example 5
Hybrid Nonisocyanate Polyurethane Network Comprising an Active
Filler
A series of particulate reinforced composites was formed using, as
a matrix, 100 parts by weight of the composition prepared as
described in Example 3. Copper aluminate (Sigma Chemical) with a
particle diameter of about 30 .mu.m was used, in the amounts shown
in Table 3, as the active filler. Quartz powder (Solel Bone, Ltd.,
Israel) with a particle diameter of about 30 .mu.m was also present
in the composites as a filler in the amounts shown in Table 3.
After the matrix and fillers were mixed in a glue mixer, the
samples were fully cured for 7 days at 20.degree. C. to form
particulate reinforced composite samples.
For determining the chemical resistance of these composites
comprising a hybrid nonisocyanate polyurethane network and an
active filler, a 30% aqueous solution of sulfuric acid was used.
The coefficient of chemical resistance K.sub.CR is defined as:
where .sigma..sub..tau. and .sigma..sub.v are the tensile
strengths, determined as described above, for a sample exposed in
30% sulfuric acid for a time .tau. months and an unexposed control,
respectively.
Table 3 summarizes the results obtained from a series of composite
samples prepared as described above with the same hybrid
nonisocyanate polyurethane network matrix and with different
amounts of copper aluminate reinforcement. These samples were
tested to determine their K.sub.CR after 6, 9 and 12 months
exposure to 30% sulfuric acid at 20.degree. C.
TABLE 3 ______________________________________ Coefficient of
Chemical Resistance to Aqueous 30% Sulfuric Acid SAMPLE NO. 21C 22
23 24 25 26 ______________________________________ Copper Aluminate
0 10 20 40 100 160 Content.sup.a Quartz Powder Content.sup.a 160
150 140 120 60 0 Exposure Time 6 months 0.87 1.12 1.14 1.06 0.98
0.98 9 months 0.62 0.98 1.06 1.08 0.99 0.92 12 months failed 0.96
1.05 1.07 0.99 0.95 ______________________________________ .sup.a
In parts by weight based on 100 parts of nonisocyanate polyurethan
network
It is apparent from the above results that even a control sample
without an active filler, sample 21C, performed well under
prolonged exposure to an aggressive medium, e.g., after 6 months
exposure to 30% sulfuric acid, having a relatively high K.sub.CR of
0.87. However, all of the above nonisocyanate polyurethane network
samples comprising an active filler retained even more of their
initial tensile strength than did the control after 6 months
exposure. In fact, the tensile strength of samples 22, 23 and 24
increased substantially over their initial tensile strength after 6
months exposure to 30% sulfuric acid, thereby demonstrating a
beneficial effect provided by including an active filler in these
sample compositions.
Even after 12 months of exposure to 30% sulfuric acid, by which
time the control sample had failed, samples 22-26 all had excellent
tensile strength retention. In fact, the tensile strength of
samples 23 and 24 increased substantially over their initial
tensile strength even after 12 months exposure to 30% sulfuric
acid.
Moreover, all of the non-exposed composite samples of nonisocyanate
polyurethane network matrix and active filler reinforcement were
much tougher than the control without an active filler. For
example, when the ellipse of failure was determined from
multi-dimensional tensile testing, the area of the ellipse
increased greatly for the actively filled composite nonisocyanate
polyurethane network samples, e.g., in some instances by more than
ten times over the non-composite control without an active
filler.
While it is apparent that the illustrative embodiments of the
invention herein disclosed fulfills the objective stated above, it
will be appreciated that numerous modifications and other
embodiments may be devised by those skilled in the art. Therefore,
it will be understood that the appended claims are intended to
cover all such modifications and embodiments which come within the
spirit and scope of the present invention.
The contents of all patents cited herein are incorporated by
reference in their entirety.
* * * * *